The present invention relates to an apparatus for changing a plate cylinder in a web-fed rotary gravure press, and more particularly to an apparatus for changing a plate cylinder which can easily and quickly change a plate cylinder.
Conventionally, in a web-fed rotary gravure press, after a certain number of sheets has been printed by a plate cylinder mounted at present on a machine, the plate cylinder is replaced with a new one. The replacement work is carried out in the following manner. Workers are deployed to both sides of the plate cylinder mounted at present (hereinafter referred to as a present plate cylinder) on the machine, the present plate cylinder is removed and conveyed to a certain place. Thereafter, a new plate cylinder to be mounted (hereinafter referred to as a new plate cylinder) is placed in a predetermined position and mounted on the machine. This replacement work is carried out for every unit of an edition. This replacement work from the present plate cylinder to the new plate cylinder by workers necessitates a great deal of labor and time. Further, since the replacement work is carried out for every unit of an edition, the printing efficiency is very low. Particularly, when the lot size of material to be printed is small, the proportion of loss time to total printing time is high thus lowerin the entire efficiency of printing.
In order to eliminate the above described drawbacks, there has been proposed an apparatus for automatically changing a plate cylinder which is provided with an elevator, capable of being raised or lowered, immediately below the plate cylinder rotatably supported by a pair of supporting mechanisms. In this apparatus, the present plate cylinder is removed outside from the elevator by a conveying mechanism, the new plate cylinder is automatically mounted on the supporting mechanisms in place of the present plate cylinder.
However, in this conventional apparatus for automatically changing a plate cylinder, since the new plate cylinder is directly conveyed by the conveying mechanism, the position of the new plate cylinder in a rotational direction is displaced while it is conveyed. As a result, the position of the new plate cylinder must be readjusted before setting. Attachment of the plate cylinder to the supporting mechanism is therefore troublesome and time-consuming.
Briefly, in the case where all replacement work is carried out by workers, a great deal of labor and time is required. On the other hand, in the conventional apparatus for automatically changing a plate cylinder, since the conveying work of the new plate cylinder cannot be performed without displacement of the plate cylinder, the replacement work of the plate cylinder is troublesome and time-consuming.